Only one neighbor was an official intervenor in the Site Evaluation Committee case, which lasted just over a year. The SEC took 16 written comments on the Merrimack project, compared to thousands so far on Northern Pass.

Quinlan says they want to apply what worked in the Merrimack process to that case and the Seacoast project, too.

"It just reinforces the importance of listening and outreach, and this is a great example of that,” he says.

Eversource hopes to get approval for the other two projects before the SEC in the next few months. The Merrimack line goes into service Dec. 20.